<template>
	<view>
		<view class="wrapper">
			  <view class="handBtn">
				  <image @click="selectColorEvent('black','#1A1A1A')" :src="selectColor === 'black'? '../static/other/color_black_selected.png': '../static/other/color_black.png'" :class="[ selectColor === 'black' ? 'color_select' : '','black-select']"></image>
				  <image @click="selectColorEvent('red','#ca262a')" :src="selectColor === 'red'? '../static/other/color_red_selected.png': '../static/other/color_red.png'"  :class="[ selectColor === 'red' ? 'color_select' : '','black-select']"></image>
				  <button @click="retDraw" class="delBtn">重写</button>
				  <button @click="saveCanvasAsImg" class="saveBtn">保存</button>
				  <button @click="previewCanvasImg" class="previewBtn">预览</button>
				  <button @click="uploadCanvasImg" class="uploadBtn">上传</button>
				  <button @click="subCanvas" class="subBtn">完成</button>
			  </view>
			  <view class="handCenter">
				 <canvas class="handWriting" :disable-scroll="true" @touchstart="uploadScaleStart" @touchmove="uploadScaleMove"
				   @touchend="uploadScaleEnd" canvas-id="handWriting"></canvas>
			  </view>
			  <view class="handRight">
				  <view class="handTitle">
					  请签名
				  </view>
			  </view>
		</view>
		
	</view>
</template>

<script>  
export default {  
	data(){
		return {
				canvasName: 'handWriting',
				ctx: '',
				canvasWidth: 0,
				canvasHeight: 0,
				transparent: 1, // 透明度
				selectColor: 'black',
				lineColor: '#1A1A1A', // 颜色
				lineSize: 1.5, // 笔记倍数
				lineMin: 0.5, // 最小笔画半径
				lineMax: 4, // 最大笔画半径
				pressure: 1, // 默认压力
				smoothness: 60, //顺滑度，用60的距离来计算速度
				currentPoint: {},
				currentLine: [], // 当前线条
				firstTouch: true, // 第一次触发
				radius: 1, //画圆的半径
				cutArea: {
					top: 0,
					right: 0,
					bottom: 0,
					left: 0
				}, //裁剪区域
				bethelPoint: [], //保存所有线条 生成的贝塞尔点；
				lastPoint: 0,
				chirography: [], //笔迹
				currentChirography: {}, //当前笔迹
				linePrack: [] //划线轨迹 , 生成线条的实际点
			};
	},
	onLoad(){
		//页面一加载则就先创建画布实例及获取其宽、高
		//1.画布的唯一标识
		let canvasName = this.canvasName
		//创建画布canvas的上下文对象
		let ctx = wx.createCanvasContext(canvasName);
		//定义个全局的上下文对象
		this.ctx = ctx;
		//创建个选择对象
		//主要用于创建一个选择器查询实例。通过这个实例，你可以选择页面中的节点，并对这些节点进行相关的操作，例如获取节点的位置信息、尺寸、样式等。
		let query = wx.createSelectorQuery()
		query.select('.handCenter').boundingClientRect(rect => {
			this.canvasWidth = rect.width
			this.canvasHeight = rect.height;
			/* 将canvas 背景设置为白底，若不设置 导出的canvas的背景为透明*/
			this.setCanvasBg('#fff');
			// this.setCanvasBg('red')
		}).exec()
	},
	
	methods:{
		
		selectColorEvent(str, color) {
			this.selectColor = str;
			this.lineColor = color;
		},
		//设置canvas背景色  不设置  导出的canvas的背景为透明
		//@params：字符串  color
		setCanvasBg(color) {
		
			/* 将canvas背景设置为 白底，不设置  导出的canvas的背景为透明 */
			//rect() 参数说明  矩形路径左上角的横坐标，左上角的纵坐标, 矩形路径的宽度, 矩形路径的高度
			//这里是 canvasHeight - 4 是因为下边盖住边框了，所以手动减了写
			this.ctx.rect(0, 0, this.canvasWidth, this.canvasHeight);
			// ctx.setFillStyle('red')
			this.ctx.setFillStyle(color);
			this.ctx.fill(); //设置填充
			this.ctx.draw(); //开画
			
		},
		
		//1. 重写
	   //调用 this.ctx.draw() 是为了确保在清空画布之后，能够正确地渲染之前的绘制命令，并在此基础上可以进行后续的绘制操作。
		retDraw() {  
		    this.ctx.clearRect(0, 0, 700, 730); // 清除指定区域的画布  
		    this.ctx.draw(); // 这行代码可能是为了将之前的绘制命令渲染到画布上  
		    this.setCanvasBg('#fff'); // 设置画布背景颜色  
		},
		
		//保存到相册
		saveCanvasAsImg(){
			//把当前画布指定区域的内容导出生成指定大小的图片。在 draw() 回调里调用该方法才能保证图片导出成功
			//1.获取图片路径
			wx.canvasToTempFilePath({
				canvasId:'hanndWriting',
				fileType:'png',
				quality: 1,//图片质量
				success(res) {
					// console.log(res.tempFilePath, 'canvas生成图片地址');
					//2.  保存到系统相册
					wx.saveImageToPhotosAlbum({
						filePath: res.tempFilePath,
						success(res){
							wx.showToast({
								title:"已保存到相册",
								duration: 2000
							})
						}
					})
				}
			})
		},
		
		//预览
		previewCanvasImg() {
			wx.canvasToTempFilePath({
				canvasId: 'handWriting',
				fileType: 'jpg',
				quality: 1, //图片质量
				success(res) {
					wx.previewImage({
						urls:[res.tempFilePath]  //预览图片 数组
					})
				}
			});
		},
		
		
		//上传
		uploadCanvasImg() {
		
			wx.canvasToTempFilePath({
				canvasId: 'handWriting',
				fileType: 'png',
				quality: 1, //图片质量
				success(res) {
					// console.log(res.tempFilePath, 'canvas生成图片地址');
					//上传
					wx.uploadFile({
						url: 'https://example.weixin.qq.com/upload', // 仅为示例，非真实的接口地址
						filePath: res.tempFilePath,
						name: 'file_signature',
						formData: {
							user: 'test'
						},
						success(res) {
							const data = res.data;
							// do something
						}
					});
				}
			});
		},
		
		//完成
		subCanvas() {
			this.ctx.draw(true, () => {
				wx.canvasToTempFilePath({
					canvasId: 'handWriting',
					fileType: 'png',
					quality: 1, //图片质量
					success(res) {
						// console.log(res.tempFilePath, 'canvas生成图片地址');
						wx.showToast({
							title: '以保存'
						});
						//保存到系统相册
						wx.saveImageToPhotosAlbum({
							filePath: res.tempFilePath,
							success(res) {
								wx.showToast({
									title: '已成功保存到相册',
									duration: 2000
								});
							}
						});
					}
				});
			});
		},
		
		//笔迹开始
		uploadScaleStart(e){
			//检查事件类型是否为 'touchstart' ,若不是 则返回false
			if(e.type != 'touchstart') return false
			//获取画布的上下文
			let ctx = this.ctx;
			//设置初始线条的颜色
			ctx.setFillStyle(this.lineColor)
			ctx.setGlobalAlpha(this.transparent)
			
			//获取当前触摸点的坐标
			let currentPoint = {
				x: e.touches[0].x,
				y: e.touches[0].y
			}
			//获取当前绘制的线条数据
			let currentLine = this.currentLine;
			//将当前点的信息（时间、距离、坐标）添加到当前线条的开头
			currentLine.unshift({
				time: new Date().getTime(),
				dis: 0, //初始距离设置为0
				x: currentPoint.x,
				y: currentLine.y
			})
			//更新当前点
			this.currentPoint = currentPoint
			//若是第一次触发 
			// 处理绘制区域：
			
			// 如果这是第一次触摸（firstTouch 为 true），则初始化 cutArea 对象，记录绘制区域的边界（上下左右）。
			// 将 firstTouch 设置为 false，以防止后续触摸再次初始化该区域。
			
			if(this.firstTouch){
				this.cutArea = {
					top: currentPoint.y,
					right: currentPoint.x,
					bottom: currentPoint.y,
					left: currentPoint.x
					}
				this.firstTouch = false
			}
			//将当前线条的点转换为线条
			this.pointToLine(currentLine)
		},
		//画两点之间的线条；参数为:line，会绘制最近的开始的两个点；
		pointToLine(line) {
			this.calcBethelLine(line);
			return;
		},
		//计算插值的方式；
		calcBethelLine(line) {
			if (line.length <= 1) {
				line[0].r = this.radius;
				return;
			}
			let x0,
				x1,
				x2,
				y0,
				y1,
				y2,
				r0,
				r1,
				r2,
				len,
				lastRadius,
				dis = 0,
				time = 0,
				curveValue = 0.5;
			if (line.length <= 2) {
				x0 = line[1].x;
				y0 = line[1].y;
				x2 = line[1].x + (line[0].x - line[1].x) * curveValue;
				y2 = line[1].y + (line[0].y - line[1].y) * curveValue;
				//x2 = line[1].x;
				//y2 = line[1].y;
				x1 = x0 + (x2 - x0) * curveValue;
				y1 = y0 + (y2 - y0) * curveValue;
			} else {
				x0 = line[2].x + (line[1].x - line[2].x) * curveValue;
				y0 = line[2].y + (line[1].y - line[2].y) * curveValue;
				x1 = line[1].x;
				y1 = line[1].y;
				x2 = x1 + (line[0].x - x1) * curveValue;
				y2 = y1 + (line[0].y - y1) * curveValue;
			}
			//从计算公式看，三个点分别是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)这个是控制点，控制点不会落在曲线上；实际上，这个点还会手写获取的实际点，却落在曲线上
			len = this.distance({
				x: x2,
				y: y2
			}, {
				x: x0,
				y: y0
			});
			lastRadius = this.radius;
			for (let n = 0; n < line.length - 1; n++) {
				dis += line[n].dis;
				time += line[n].time - line[n + 1].time;
				if (dis > this.smoothness) break;
			}
		
			this.radius = Math.min((time / len) * this.pressure + this.lineMin, this.lineMax) * this.lineSize;
			line[0].r = this.radius;
			//计算笔迹半径；
			if (line.length <= 2) {
				r0 = (lastRadius + this.radius) / 2;
				r1 = r0;
				r2 = r1;
				//return;
			} else {
				r0 = (line[2].r + line[1].r) / 2;
				r1 = line[1].r;
				r2 = (line[1].r + line[0].r) / 2;
			}
			let n = 5;
			let point = [];
			for (let i = 0; i < n; i++) {
				let t = i / (n - 1);
				let x = (1 - t) * (1 - t) * x0 + 2 * t * (1 - t) * x1 + t * t * x2;
				let y = (1 - t) * (1 - t) * y0 + 2 * t * (1 - t) * y1 + t * t * y2;
				let r = lastRadius + ((this.radius - lastRadius) / n) * i;
				point.push({
					x: x,
					y: y,
					r: r
				});
				if (point.length == 3) {
					let a = this.ctaCalc(point[0].x, point[0].y, point[0].r, point[1].x, point[1].y, point[1].r, point[2].x, point[2]
						.y, point[2].r);
					a[0].color = this.lineColor;
					// let bethelPoint = this.bethelPoint;
					// bethelPoint = bethelPoint.push(a);
					this.bethelDraw(a, 1);
					point = [{
						x: x,
						y: y,
						r: r
					}];
				}
			}
			this.currentLine = line;
		},
		//求两点之间距离
		distance(a, b) {
			let x = b.x - a.x;
			let y = b.y - a.y;
			return Math.sqrt(x * x + y * y);
		},
		ctaCalc(x0, y0, r0, x1, y1, r1, x2, y2, r2) {
			let a = [],
				vx01,
				vy01,
				norm,
				n_x0,
				n_y0,
				vx21,
				vy21,
				n_x2,
				n_y2;
			vx01 = x1 - x0;
			vy01 = y1 - y0;
			norm = Math.sqrt(vx01 * vx01 + vy01 * vy01 + 0.0001) * 2;
			vx01 = (vx01 / norm) * r0;
			vy01 = (vy01 / norm) * r0;
			n_x0 = vy01;
			n_y0 = -vx01;
			vx21 = x1 - x2;
			vy21 = y1 - y2;
			norm = Math.sqrt(vx21 * vx21 + vy21 * vy21 + 0.0001) * 2;
			vx21 = (vx21 / norm) * r2;
			vy21 = (vy21 / norm) * r2;
			n_x2 = -vy21;
			n_y2 = vx21;
			a.push({
				mx: x0 + n_x0,
				my: y0 + n_y0,
				color: '#1A1A1A'
			});
			a.push({
				c1x: x1 + n_x0,
				c1y: y1 + n_y0,
				c2x: x1 + n_x2,
				c2y: y1 + n_y2,
				ex: x2 + n_x2,
				ey: y2 + n_y2
			});
			a.push({
				c1x: x2 + n_x2 - vx21,
				c1y: y2 + n_y2 - vy21,
				c2x: x2 - n_x2 - vx21,
				c2y: y2 - n_y2 - vy21,
				ex: x2 - n_x2,
				ey: y2 - n_y2
			});
			a.push({
				c1x: x1 - n_x2,
				c1y: y1 - n_y2,
				c2x: x1 - n_x0,
				c2y: y1 - n_y0,
				ex: x0 - n_x0,
				ey: y0 - n_y0
			});
			a.push({
				c1x: x0 - n_x0 - vx01,
				c1y: y0 - n_y0 - vy01,
				c2x: x0 + n_x0 - vx01,
				c2y: y0 + n_y0 - vy01,
				ex: x0 + n_x0,
				ey: y0 + n_y0
			});
			a[0].mx = a[0].mx.toFixed(1);
			a[0].mx = parseFloat(a[0].mx);
			a[0].my = a[0].my.toFixed(1);
			a[0].my = parseFloat(a[0].my);
			for (let i = 1; i < a.length; i++) {
				a[i].c1x = a[i].c1x.toFixed(1);
				a[i].c1x = parseFloat(a[i].c1x);
				a[i].c1y = a[i].c1y.toFixed(1);
				a[i].c1y = parseFloat(a[i].c1y);
				a[i].c2x = a[i].c2x.toFixed(1);
				a[i].c2x = parseFloat(a[i].c2x);
				a[i].c2y = a[i].c2y.toFixed(1);
				a[i].c2y = parseFloat(a[i].c2y);
				a[i].ex = a[i].ex.toFixed(1);
				a[i].ex = parseFloat(a[i].ex);
				a[i].ey = a[i].ey.toFixed(1);
				a[i].ey = parseFloat(a[i].ey);
			}
			return a;
		},
		bethelDraw(point, is_fill, color) {
			let ctx = this.ctx;
			ctx.beginPath();
			ctx.moveTo(point[0].mx, point[0].my);
			if (undefined != color) {
				ctx.setFillStyle(color);
				ctx.setStrokeStyle(color);
			} else {
				ctx.setFillStyle(point[0].color);
				ctx.setStrokeStyle(point[0].color);
			}
			for (let i = 1; i < point.length; i++) {
				ctx.bezierCurveTo(point[i].c1x, point[i].c1y, point[i].c2x, point[i].c2y, point[i].ex, point[i].ey);
			}
			ctx.stroke();
			if (undefined != is_fill) {
				ctx.fill(); //填充图形 ( 后绘制的图形会覆盖前面的图形, 绘制时注意先后顺序 )
			}
			ctx.draw(true);
		},
		
		// 笔迹移动
		uploadScaleMove(e) {
			if (e.type != 'touchmove') return false;
			if (e.cancelable) {
				// 判断默认行为是否已经被禁用
				if (!e.defaultPrevented) {
					e.preventDefault();
				}
			}
			let point = {
				x: e.touches[0].x,
				y: e.touches[0].y
			};
		
			//测试裁剪
			if (point.y < this.cutArea.top) {
				this.cutArea.top = point.y;
			}
			if (point.y < 0) this.cutArea.top = 0;
		
			if (point.x > this.cutArea.right) {
				this.cutArea.right = point.x;
			}
			if (this.canvasWidth - point.x <= 0) {
				this.cutArea.right = this.canvasWidth;
			}
			if (point.y > this.cutArea.bottom) {
				this.cutArea.bottom = point.y;
			}
			if (this.canvasHeight - point.y <= 0) {
				this.cutArea.bottom = this.canvasHeight;
			}
			if (point.x < this.cutArea.left) {
				this.cutArea.left = point.x;
			}
			if (point.x < 0) this.cutArea.left = 0;
		
			this.lastPoint = this.currentPoint;
			this.currentPoint = point;
		
			let currentLine = this.currentLine;
			currentLine.unshift({
				time: new Date().getTime(),
				dis: this.distance(this.currentPoint, this.lastPoint),
				x: point.x,
				y: point.y
			});
		
			this.pointToLine(currentLine);
		},
		// 笔迹结束
		uploadScaleEnd(e) {
			if (e.type != 'touchend') return 0;
			let point = {
				x: e.changedTouches[0].x,
				y: e.changedTouches[0].y
			};
			this.lastPoint = this.currentPoint;
			this.currentPoint = point;
		
			let currentLine = this.currentLine;
			currentLine.unshift({
				time: new Date().getTime(),
				dis: this.distance(this.currentPoint, this.lastPoint),
				x: point.x,
				y: point.y
			});
		
			if (currentLine.length > 2) {
				var info = (currentLine[0].time - currentLine[currentLine.length - 1].time) / currentLine.length;
				//$("#info").text(info.toFixed(2));
			}
			//一笔结束，保存笔迹的坐标点，清空，当前笔迹
			//增加判断是否在手写区域；
			this.pointToLine(currentLine);
			var currentChirography = {
				lineSize: this.lineSize,
				lineColor: this.lineColor
			};
			var chirography = this.chirography;
			chirography.unshift(currentChirography);
			this.chirography = chirography;
		
			var linePrack = this.linePrack;
			linePrack.unshift(this.currentLine);
			this.linePrack = linePrack;
			this.currentLine = [];
		},
	}
  
};  
</script>
<style>
	page {
		background: #fbfbfb;
		height: auto;
		overflow: hidden;
	}

	.wrapper {
		width: 100%;
		height: 95vh;
		margin: 30rpx 0;
		overflow: hidden;
		display: flex;
		align-content: center;
		flex-direction: row;
		justify-content: center;
		font-size: 28rpx;
	}
	
	.handBtn {
		height: 95vh;
		display: inline-flex;
		flex-direction: column;
		justify-content: space-between;
		flex: 1;
	}
	.handBtn button {
		font-size: 27rpx;
		}

	.delBtn {
		position: absolute;
		top: 250rpx;
		left: 0rpx;
		transform: rotate(90deg);
		color: #666;
	}
	.delBtn image {
		position: absolute;
		top: 13rpx;
		left: 25rpx;
	}
	
	.subBtn {
		position: absolute;
		bottom: 52rpx;
		left: -3rpx;
		display: inline-flex;
		transform: rotate(90deg);
		background: #008ef6;
		color: #fff;
		margin-bottom: 30rpx;
		text-align: center;
		justify-content: center;
	}
	
	/*Peach - 新增 - 保存*/
	
	.saveBtn {
		position: absolute;
		top: 375rpx;
		left: 0rpx;
		transform: rotate(90deg);
		color: #666;
	}
	
	.previewBtn {
		position: absolute;
		top: 500rpx;
		left: 0rpx;
		transform: rotate(90deg);
		color: #666;
	}
	
	.uploadBtn {
		position: absolute;
		top: 625rpx;
		left: 0rpx;
		transform: rotate(90deg);
		color: #666;
	}
	
	/*Peach - 新增 - 保存*/
	
	.black-select {
		width: 60rpx;
		height: 60rpx;
		position: absolute;
		top: 30rpx;
		left: 25rpx;
	}
	
	.black-select.color_select {
		width: 90rpx;
		height: 90rpx;
		top: 100rpx;
		left: 10rpx;
	}
	
	.red-select {
		width: 60rpx;
		height: 60rpx;
		position: absolute;
		top: 140rpx;
		left: 25rpx;
	}
	
	.red-select.color_select {
		width: 90rpx;
		height: 90rpx;
		top: 120rpx;
		left: 10rpx;
	}
	
	
	
	.handCenter {
		border: 4rpx dashed #e9e9e9;
		flex: 5;
		overflow: hidden;
		box-sizing: border-box;
	}
	
	.handWriting {
		background: #fff;
		width: 100%;
		height: 95vh;
	}

	
	.handRight {
		display: inline-flex;
		align-items: center;
	}
	
	.handTitle {
		transform: rotate(90deg);
		flex: 1;
		color: #666;
	}
</style>
